Visual edge rendering using geometry shader clipping

A method for presenting a three-dimensional (3D) object on a display screen, comprising:

• receiving, at a graphics processing unit, object data representing a model of a 3D object, the object data including a plurality of interrelated polygons;
• receiving, at the graphics processing unit, coordinates for one or more clipping boundaries, the one or more clipping boundaries defining a presentation region that overlaps at least in part with visible portions of the display screen;
• using a geometry shader, performing per-polygon clipping on each polygon of the object data that intersects with at least one clipping boundary to generate a clipped model of the 3D object;
• using the geometry shader, designating each primitive within the clipped model that intersects with one or more clipping boundaries as an edge primitive;
• using a pixel shader, rendering each pixel derived from an edge primitive using a predetermined edge treatment;
• and
• presenting, on the display screen, the clipped model of the 3D object such that the predetermined edge treatment is visible at the clipping boundaries.

A head-mounted display device, comprising:

• a see-through display;
• and
• a controller, configured to:
• receive, at a graphics processing unit, object data representing a model of a 3D object, the object data including a plurality of interrelated polygons;
• receive, at the graphics processing unit, coordinates for one or more clipping boundaries, the one or more clipping boundaries defining a presentation region that overlaps at least in part with visible portions of the see-through display;
• using a geometry shader, perform per-polygon clipping on each polygon of the object data that intersects with at least one clipping boundary;
• using the geometry shader, designate each primitive within the clipped model that intersects with one or more clipping boundaries as an edge primitive;
• at a pixel shader, receive object data representing a clipped model of the 3D object;
• using the pixel shader, render each pixel derived from an edge primitive using a predetermined edge treatment;
• and
• at the pixel shader, render only pixels of the 3D object that lie within the presentation region.